//! A2A Streaming Support
//!
//! 实现流式响应和实时通信功能

use crate::types::*;
use crate::A2AResult;
use chrono::{DateTime, Utc};
use serde::{Deserialize, Serialize};
use serde_json::json;

/// 流式响应类型
#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(tag = "type")]
pub enum StreamResponse {
    /// 任务状态更新
    StatusUpdate {
        task_id: String,
        status: TaskStatus,
        timestamp: DateTime<Utc>,
    },
    /// 部分结果
    PartialResult {
        task_id: String,
        content: String,
        progress: Option<f64>,
        timestamp: DateTime<Utc>,
    },
    /// 工件
    Artifact {
        task_id: String,
        artifact: Artifact,
        timestamp: DateTime<Utc>,
    },
    /// 错误
    Error {
        task_id: String,
        error: String,
        timestamp: DateTime<Utc>,
    },
    /// 完成
    Complete {
        task_id: String,
        final_result: Option<String>,
        timestamp: DateTime<Utc>,
    },
}

impl StreamResponse {
    /// 获取任务ID
    pub fn task_id(&self) -> &str {
        match self {
            StreamResponse::StatusUpdate { task_id, .. } => task_id,
            StreamResponse::PartialResult { task_id, .. } => task_id,
            StreamResponse::Artifact { task_id, .. } => task_id,
            StreamResponse::Error { task_id, .. } => task_id,
            StreamResponse::Complete { task_id, .. } => task_id,
        }
    }

    /// 获取内容
    pub fn content(&self) -> Option<&str> {
        match self {
            StreamResponse::PartialResult { content, .. } => Some(content),
            StreamResponse::Error { error, .. } => Some(error),
            StreamResponse::Complete { final_result, .. } => final_result.as_deref(),
            _ => None,
        }
    }

    /// 获取进度
    pub fn progress(&self) -> Option<f64> {
        match self {
            StreamResponse::PartialResult { progress, .. } => *progress,
            _ => None,
        }
    }

    /// 获取错误信息
    pub fn error(&self) -> Option<&str> {
        match self {
            StreamResponse::Error { error, .. } => Some(error),
            _ => None,
        }
    }

    /// 获取状态
    pub fn status(&self) -> Option<&TaskStatus> {
        match self {
            StreamResponse::StatusUpdate { status, .. } => Some(status),
            _ => None,
        }
    }

    /// 获取最终结果
    pub fn final_result(&self) -> Option<&str> {
        match self {
            StreamResponse::Complete { final_result, .. } => final_result.as_deref(),
            _ => None,
        }
    }
}

/// 流式响应发送器
#[derive(Debug, Clone)]
pub struct StreamSender {
    // Simplified for now
}

impl StreamSender {
    /// 创建新的流式发送器
    pub fn new() -> (Self, ()) {
        (Self { }, ())
    }

    /// 发送状态更新
    pub fn send_status_update(&self, _task_id: &str, _status: TaskStatus) -> A2AResult<()> {
        // TODO: Implement actual streaming
        Ok(())
    }

    /// 发送部分结果
    pub fn send_partial_result(&self, _task_id: &str, _content: String, _progress: Option<f64>) -> A2AResult<()> {
        // TODO: Implement actual streaming
        Ok(())
    }

    /// 发送工件
    pub fn send_artifact(&self, _task_id: &str, _artifact: Artifact) -> A2AResult<()> {
        // TODO: Implement actual streaming
        Ok(())
    }

    /// 发送错误
    pub fn send_error(&self, _task_id: &str, _error: String) -> A2AResult<()> {
        // TODO: Implement actual streaming
        Ok(())
    }

    /// 发送完成信号
    pub fn send_complete(&self, _task_id: &str, _final_result: Option<String>) -> A2AResult<()> {
        // TODO: Implement actual streaming
        Ok(())
    }

    /// 检查连接是否仍然活跃
    pub fn is_connected(&self) -> bool {
        true // TODO: Implement actual connection check
    }

    /// 断开连接
    pub fn disconnect(&mut self) {
        // TODO: Implement actual disconnection
    }
}

/// 流式任务管理器
#[derive(Debug)]
pub struct StreamTaskManager {
    // Simplified for now
}

impl StreamTaskManager {
    /// 创建新的流式任务管理器
    pub fn new() -> Self {
        Self { }
    }

    /// 注册任务流
    pub fn register_stream(&mut self, _task_id: &str) -> (StreamSender, ()) {
        let sender = StreamSender::new();
        (sender.0, ())
    }

    /// 获取任务流发送器
    pub fn get_sender(&self, _task_id: &str) -> Option<&StreamSender> {
        None // TODO: Implement actual storage
    }

    /// 移除任务流
    pub fn remove_stream(&mut self, _task_id: &str) {
        // TODO: Implement actual removal
    }

    /// 获取活跃流数量
    pub fn active_streams_count(&self) -> usize {
        0 // TODO: Implement actual counting
    }

    /// 清理已关闭的流
    pub fn cleanup_closed_streams(&mut self) {
        // TODO: Implement actual cleanup
    }
}

impl Default for StreamTaskManager {
    fn default() -> Self {
        Self::new()
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_stream_sender_creation() {
        let (sender, _) = StreamSender::new();
        assert!(sender.is_connected());
    }

    #[test]
    fn test_stream_task_manager_creation() {
        let manager = StreamTaskManager::new();
        assert_eq!(manager.active_streams_count(), 0);
    }

    #[test]
    fn test_stream_response_serialization() {
        let response = StreamResponse::StatusUpdate {
            task_id: "test".to_string(),
            status: TaskStatus::new(TaskState::Working),
            timestamp: Utc::now(),
        };
        
        let json = serde_json::to_string(&response);
        assert!(json.is_ok());

        let deserialized: StreamResponse = serde_json::from_str(&json.unwrap()).unwrap();
        assert_eq!(response.task_id(), deserialized.task_id());
        assert_eq!(response.status().unwrap().state, deserialized.status().unwrap().state);
    }

    #[test]
    fn test_stream_partial_result() {
        let response = StreamResponse::PartialResult {
            task_id: "test_task".to_string(),
            content: "Partial data".to_string(),
            progress: Some(0.75),
            timestamp: Utc::now(),
        };
        
        let json = serde_json::to_string(&response).unwrap();
        let deserialized: StreamResponse = serde_json::from_str(&json).unwrap();
        
        assert_eq!(deserialized.task_id(), "test_task");
        assert_eq!(deserialized.content(), Some("Partial data"));
        assert_eq!(deserialized.progress(), Some(0.75));
    }

    #[test]
    fn test_stream_error_response() {
        let error_response = StreamResponse::Error {
            task_id: "failed_task".to_string(),
            error: "Processing failed".to_string(),
            timestamp: Utc::now(),
        };
        
        let json = serde_json::to_string(&error_response).unwrap();
        let deserialized: StreamResponse = serde_json::from_str(&json).unwrap();
        
        assert_eq!(deserialized.task_id(), "failed_task");
        assert_eq!(deserialized.error(), Some("Processing failed"));
    }

    #[test]
    fn test_stream_complete_response() {
        let response = StreamResponse::Complete {
            task_id: "completed_task".to_string(),
            final_result: Some("Task completed successfully".to_string()),
            timestamp: Utc::now(),
        };
        
        let json = serde_json::to_string(&response).unwrap();
        let deserialized: StreamResponse = serde_json::from_str(&json).unwrap();
        
        assert_eq!(deserialized.task_id(), "completed_task");
        assert_eq!(deserialized.final_result(), Some("Task completed successfully"));
    }
}